New Research

Researchers Have Figured Out How to Spot Fake Ancient Pottery Using the Earth’s Magnetic Field

The magnetic North Pole has shifted over the millennia, leaving clues in the minerals that make up clay antiquities

Sonja Anderson | Daily Correspondent

September 4, 2026 7:45 a.m.

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Forgers, beware. Researchers just discovered how to determine whether any piece of pottery is ancient or not—by reading its magnetic signatures.

A team at the Scripps Institution of Oceanography at the University of California, San Diego, details their new method in a study published this week in the Proceedings of the National Academy of Sciences. Per a statement from the institute, the technique could help weed out falsified archaeological artifacts around the world.

“I hope that our new method will be useful for museum curators who wish to display only authentic artifacts, for archaeologists and historians studying the societies which created them, and for law enforcement authorities in their effort to eliminate illicit antiquities trade, which involves looting archaeological sites and forgery,” study co-author Yoav Vaknin says in the statement.

When clay particles are fired in a kiln, their magnetic field orients toward Earth’s magnetic North Pole. That’s because clay objects contain ferromagnetic minerals, Vaknin, who specializes in archaeomagnetic dating, told Artnet’s Vittoria Benzine in 2022. “On the atomic level, one can imagine the magnetic signal of these minerals as a tiny needle of a compass,” he said.

That magnetic signal, frozen in large clay particles as they cool, is called thermal remanent magnetization (TRM), write the researchers. Because the location of the pole is constantly shifting, the TRM of ancient pottery points in a slightly different direction than that of pottery made today.

But then, after the clay cools, it’s exposed to “an ambient geomagnetic field in a different direction,” write the researchers. As Vaknin tells Haaretz’s Ariel David, over centuries, some of the clay’s minerals acquire a second, weaker signal: a record of different intensity and direction of the magnetic field. This signal is called the viscous remanent magnetization (VRM).

Scientists have known about VRM for more than a century, and they’ve attempted to use it to date geological events, reports Haaretz. But the signal is so weak, researchers usually treat it as “noise,” an obstacle in front of the TRM.

For their study, Vaknin and his co-authors tested 45 pottery samples: 4 excavated shards of ancient pottery, 15 excavated ancient royal Judean storage jars, 6 modern pottery vessels fired in traditional kilns, 16 clay seal impressions fired in modern kilns and 4 souvenir pottery vessels sold in Jerusalem. The researchers baked these samples, heating them up in increments of 18 degrees Fahrenheit. They aimed to measure at which point the VRM signals of each piece disappear, leaving only the TRMs.

“The resolution we require is not very high; we just want to know if an object is ancient or modern,” Vaknin tells Haaretz.

The researchers determined that any sample older than a millennium had to be heated to at least 234 degrees Fahrenheit before its VRM was erased. New pottery samples’ VRMs, meanwhile, could be wiped at lower temperatures.

The researchers hope the threshold they’ve discovered will aid future investigations into artifact forgery. Fakes proliferate in Israel, China, Mexico and every other archaeologically rich country, “particularly in places where treachery abounds,” co-author Lisa Tauxe says in the statement. In the study, the researchers mention the case of the “James Ossuary,” a possibly fake burial box that supposedly belonged to Jesus Christ’s brother. After a seven-year criminal trial, “the court ruled that the forgery had not been proven beyond reasonable doubt,” the co-authors write.

The team already tried their new method on three “artifacts of questionable authenticity,” confiscated by the Israel Antiquities Authority, they write. Their results suggest that all three clay artifacts were in fact fired in ancient times. This illuminates the method’s other usage: finding real artifacts that have been looted and illegally traded—another constant battle for researchers.

“There is a problem in the authentication field: On one side are the scientists who publish their findings, and on the other side are the forgers who do their work secretly,” Vaknin tells Haaretz. “So it’s hard for us to be ahead of the forgers since they can read our papers and figure out ways to trick our methods.”

Sonja Anderson is a daily correspondent for Smithsonian magazine who covers art, archaeology and culture, from newly discovered artifacts to the latest art heists.